4 ms·
Intel's more likely argument is that they can't do that many because their decoders and ROB aren't wide enough to keep up. Given how huge their decode units are
by hajile 6y ago
Intel's more likely argument is that they can't do that many because their decoders and ROB aren't wide enough to keep up. Given how huge their decode units are (about as big as all their integer ALUs), I don't know how x86 will actually solve this issue.
- btown 6y agoCould Intel adapt a Rosetta 2-style approach? Preprocess binaries to replace ancient instructions with modern equivalents, and be able to use smaller decode units? Would the gains be worth the translation requirements?
- arghwhat 6y agoNo, Intel needs to approach this from hardware alone. Apple has more freedom as they only have to worry about support from their own OS, and even only the latest revision.
- klodolph 6y agoI might call that the Transmeta approach. Back in the early 2000s, Transmeta offered x86-compatible systems that ran a proprietary VLIW core with software translation. The resulting system looked like an x86 system to the OS and was more power-efficient than contemporary x86 systems from other vendors. Intel has a perpetual license for all Transmeta patents and applications.
- rbanffy 6y agoDoes the reorder buffer in x86 processors operate on the x86 instructions or the µOPs?
- foobiekr 6y agoThe company that built the original Rosetta, actually apple branding on top of QuickTransit, actually could do x86 to x86 translation in their product and found that even when low hanging fruit was theoretically available it was challenging to extract. I don’t think the x86 stuff we are talking about is easy to extract. Instead this seems like something that wants an intermediate code + install time specializer a la mainframes.
- glangdale 6y agoThere are a couple distinct issues here - M1 is both wider than recent x86 but also more orthogonal. I'm not sure that decode is the bottleneck for all code - a lot of code could be played out of a pre-decoded uop cache or the LSD. People always return to decode as an explanation as it's an attractive RISC vs CISC morality tale. I also don't know how much of the decode unit is devoted to legacy support and MSROM, which doesn't necessarily have to scale the same way as the simple decoders.